Tenofovir Disoproxil is chemically known as 9-[-2-(R)-[[bis[[(isopropoxycarbonyl)oxy]methoxy]phosphinoyl]methoxy]propyl]-adenine, having the following structural formula-I.

Tenofovir is a highly potent antiviral agent, particularly for the therapy or prophylaxis of retroviral infections and belongs to a class of drugs called Nucleotide Reverse Transcriptase Inhibitors (NRTI) which blocks reverse transcriptase an enzyme crucial to viral production in HIV-infected people.
Tenofovir Disoproxil and its pharmaceutically acceptable salts were first disclosed in U.S. Pat. No. 5,922,695. This patent discloses the preparation of Tenofovir Disoproxil by the esterification of Tenofovir with chloromethyl isopropyl carbonate using 1-methyl-2-pyrrolidinone and triethylamine. In this patent Tenofovir Disoproxil is converted into its Fumarate salt without isolation.
PCT Publication WO 2008007392 discloses process for the preparation of Tenofovir Disoproxil fumarate, wherein the isolated crystalline Tenofovir Disoproxil is converted into fumarate salt.
Tenofovir Disoproxil processes in the prior art are similar to process disclosed in product patent U.S. Pat. No. 5,922,695. According to the prior art processes, Tenofovir Disoproxil fumarate obtained is having low yields and also show the presence of impurities such as dimers.
Thus the present invention provides an improved process for the preparation of Tenofovir Disoproxil and its pharmaceutically acceptable salts with improved yield and quality.